Extraction of lead from petroleum products employing aqueous iodine monochloride



United States Patent l U.S. Cl. 208-251 4 Claims ABSTRACT OF THE DISCLOSURE Lead alkyl containing petroleum products, particularly gasoline and catalytic reformer feedstocks, are freed from their lead content by treatment with aqueous iodine monochloride.

This invention relates to the extraction of lead from hydrocarbon feedstock, gasoline and other petroleum products.

The addition of lead compounds, especially lead alkyls such as tetraethyl lead and tetramethyl lead, to gasoline and other petroleum products is common practice. For certain purposes it is necessary subsequently to extract the lead from the gasoline. For example it may be necessary to extract the lead if the gasoline is to be subjected to reprocessing, for example, in a catalytic reformer in which the gasoline may be used as a feedstock or feedstock supplement. In this case it is important that the lead be reduced to as low a level as possible, preferably to below 50 parts per thousand million, in order to minimise poisoning of the catalyst, which is usually platinum.

Known methods for the extraction of lead from petroleum products involve the extraction of the lead by treatment of the leaded product with hydrochloric or sulphuric acid. The former procedure forms the basis of the standard methods for the determination of lead in gasoline, IP 96/64 and ASTM D526. Whilst these methods are satisfactory for analytical purposes and small scale operations they are not suitable for application on a large scale.

In accordance with the present invention a method of extracting lead from gasoline and other petroleum products has been found which, being quick and substantially 100% eflicient, is capable of application on a large scale. The invention is based on the discovery that lead alkyls in gasoline or other petroleum products will react quantitatively with iodine monochloride to form water soluble dialkyl lead halides.

The method of the present invention therefore comprises treating the lead alkyl containing gasoline or other lead alkyl containing petroleum product with an aqueous solution of iodine monochloride, thoroughly mixing the inorganic phase with the organic phase, and separating the organic phase from the inorganic phase. By this method substantially complete extraction of the lead from the organic phase into the inorganic phase is obtained leaving the gasoline or other petroleum product substantially free of lead.

Since the reaction of the iodine monochloride with the lead alkyl is quantitative the amount of iodine monochloride can be stoichiometric in relation to the amount of lead alkyl present in the petroleum product. More usually, however, the amount of iodine monochloride used will be in excess of stoichiometric.

The concentration of the iodine monochloride solution used in the method of the invention will, of course, vary 3,481,866 Patented Dec. 2, 1969 with the volume of gasoline or petroleum product to be treated. As a matter of convenience the solutions used will usually be in the range 0.1-2.0 molar. Where the petroleum product contains any significant amount of olefin higher amounts of iodine monochloride will be used because iodine monochloride reacts readily with an olefinic double bond.

The extraction is performed quite conveniently at room temperature.

In order to demonstrate the extraction of lead alkyls from petroleum products in accordance with this invention a number of test samples were made up by blending various proportions of virgin naphtha, isooctane and kerosine. The samples were made up to simulate petroleum ranging from a typical catalytic reformer feedstock on the one hand to an aviation turbine fuel on the other. A known quantity of lead alkyl, either tetramethyl lead, tetraethyl lead or a mixed lead alkyl obtained by a rearrangement reaction of tetraethyl lead and tetramethyl lead, was added to each sample.

Various volumes of each sample Were taken and shaken at room temperature in a separating funnel with 10 ml. portions of a 1.0 molar aqueous solution of iodine monochloride. After shaking for three minutes the inorganic phase was separated and the organic phase washed three times with 10 ml. portions of water. The washings were added to the separated inorganic phase and the lead content of the collected inorganic phase was determined colorimetrically by the well known dithizonate procedure. The results were as follows, the weight of lead extracted is the average of two determinations.

These results clearly demonstrate the substantially complete extraction which is achieved by the method of the present invention. They also clearly demonstrate the efliciency of a single extraction which is maintained even with sample: extractant ratios as high as :1.

Whilst the invention is particularly applicable to the extraction of lead from catalytic reformer feedstocks, it may also be applied to the extraction of lead from a Wide range of petroleum products ranging from crude oil to light petroleum fractions.

We claim:

1. The process which comprises treating a petroleum product containing lead alkyl with an aqueous solution of iodine monochloride, thoroughly mixing the inorganic phase with the organic phase, and subsequently separating the two phases, thereby removing the lead from the said petroleum product.

2. The process of claim 1, wherein the amount of iodine monochloride used to treat the lead alkyl-containing petroleum product is in excess of the stoichiometric amount required to react with the lead alkyl in the product under treatment.

3. The process of claim 1 wherein the iodine monochloride solution used is 0.1-2.0 molar.

4. The process of claim 1, wherein the lead alkyl- FOREIGN PATENTS containing product under treatment is a catalytic reformer 1 126 1968 Great Britain feedstock.

References Clted DELBERT E. GANTZ, Primary Examiner UNITED STATES PATENTS 5 J. N. NELSON, Assistant Examiner 2,504,134 5/1948 Kharasch 196-44 2,969,320 1/1961 Shapiro et a1 208251 US. Cl. X.R.

2,729,593 1/1956 Garwood 196-35 20888 

